DTC P0116: ECT Sensor Performance: Description

Engine Coolant Temperature (ECT) sensor is a thermistor that varies resistance according to changes in engine coolant temperature. ECT sensor resistance is high when coolant temperature is low. Resistance drops when coolant temperature increases. PCM provides a 5-volt reference and a ground to ECT sensor. During cold start, ECT and IAT readings are compared. DTC sets after PCM verifies proper operation of IAT sensor and difference between ECT and IAT reading does not fall within an acceptable range.